If postage is not on a letter, is it always returned to the return address? What is the return address is in a different state from where it was mailed?
This can be closed since it is illegal.
It isn’t illegal to forget to put a stamp on an envelope and have the Post Office return it to you. To answer the OP’s question: It doesn’t make any difference whether you’re living in a different state from your addressee–the Post Office will still return it to you for postage.
No, I was looking for a way to send mail for free.
Get elected to public office and indulge yourself in the franking privilege.
http://www.house.gov/cha/franking/what_is_the_frank_/body_what_is_the_frank_.html
That’s about it.